Which measuring scales are displayed by frequency distribution polygons?

• A. Either interval or ratio scales
• B. Only ratio scales
• C. Either nominal or ordinal scales
• D. Only nominal scales

Answer: (A)

Frequency distribution polygons are created by plotting the frequency for each class against the class midpoint on a numeric axis and then drawing straight lines between those points. This relies on the horizontal axis representing a numeric scale with equal spacing between successive points, which only interval or ratio data provide. Nominal data have no meaningful order or distance between categories, and ordinal data have order without guaranteed equal intervals, so midpoints and equal spacing aren’t appropriate for a true polygon. Therefore, frequency distribution polygons are displayed for interval or ratio scales.